3 newly discovered nearby planets are a game changer in the hunt for alien life

Artist's
concept of a rocky Earth-sized exoplanet in the habitable zone of
its host star, possibly compatible with Kepler-186f’s known
data.NASA/SETI/JPL

An international team of astronomers has discovered three
Earth-sized exoplanets, all orbiting the same star just 40
light-years from us, the 16-nation intergovernmental research
organization ESO reported on
Monday.

The scientists have deemed all three planets potentially
habitable, an exciting turn in the hunt for "exoplanets," a term
for planets that orbit a star other than our sun.

And it could bring us closer to finding extraterrestrial life.

Star systems like this are promising places to detect alien life,
Michaël Gillon, lead author of the paper presenting the
discovery, said in an ESO press
release.

“If we want to find life elsewhere in the Universe, this is where
we should start to look," he said.

The hunt for aliens

The host star is an ultracool dwarf star — a type of cool, red
star. Most of the time these stars are too small and faint to be
detected by optical telescopes, and this star is no exception.

"Why are we trying to detect Earth-like planets around the
smallest and coolest stars in the solar neighborhood? The reason
is simple: systems around these tiny stars are the only places
where we can detect life on an Earth-sized exoplanet with our
current technology,” Gillon said.

The astronomers discovered the planets using a telescope in Chile
called TRAnsiting Planets and PlanetesImals Small Telescope
(TRAPPIST). The telescope is designed to focus on nearby dwarf
stars and search for planets orbiting them.

Because light from the star is dimming at regular intervals, it
suggests that several planets are orbiting it. The star is about
an eighth the size of the sun, half the temperature, and almost
2,000 times fainter. This is the first time astronomers have ever
found any planets orbiting a star this small and dim.

Sweet spots

The scientists determined that the third planet, located farthest
from its star, might be within the star's habitable zone.

Because of their closeness to the star, the other two planets are
likely tidally locked, with one side always facing the star and
the other always facing away.

Although the sides facing the star would be too hot to host any
lifeforms and the sides facing away would be too cold and dark,
the planets might contain "sweet spots." If the planets have
atmospheres or even possibly oceans, heat from the star might be
more evenly distributed, creating regions that just might be
suitable for life.

"The kind of planets we've found are very exciting from the
perspective of searching for life in the universe beyond Earth,"
Adam Burgasser, a professor of physics at the University of
California San Diego's Center for Astrophysics and Space
Sciences, said in a
press release.

Scientists will need to further study the planets to determine if
they are actually capable of harboring life.

One way they'll do this is by looking at the effect that the
atmosphere of the planets has on the light reaching Earth.
Because of the star's size and dimness, it won't drown out these
planetary signals, allowing scientists to get a better look.

Scientists should eventually be able to study their composition
and atmosphere more deeply as they look for signals of life.

"These planets are so close, and their star so small, we can
study their atmosphere and composition, and further down the
road, which is within our generation, assess if they are actually
inhabited," coauthor Julien de Wit, a postdoc in the Department
of Earth, Atmospheric, and Planetary Sciences, said in an MIT
press release.

These findings open the door for future studies of other
ultracool dwarf stars, which are long-lived and common in the
Milky Way. Around three fourths of all stars and 15% of the stars
near to the Sun are ultracool dwarf stars.

With the help of several giant telescopes that are under
construction, de Wit says, scientists will soon be able to study
the atmospheric composition of these planets to explore them for
water and traces of biological activity.